It is. It's MOSTLY for denaturing enzymes while you're doing a rather long fly sparge. If you didn't raise the temp, you'd still be converting over that 45-60 minutes which you may not want. It has a side effect of loosening a bit more sugar but it's absolutely NOT necessary with batch sparging.
The best efficiency I've ever gotten was 94% and it was taking 3 distinct runnings. One following the mash (no mash out infusion), then two runnings following half sparge volume infusions. I don't recommend a mash out infusion unless you want to reduce your number of runnings to two (for a slight reduction is task load/time).
In summary you have two choices:
#1
mash
infuse an amount equal to your grain absorption (about .1 gallons per pound of grain) for your mash out (200F).
stir, vorlauf and drain.
Infuse single batch sparge volume @ 170F, stir, vorlauf and drain.
two runnings, both at elevated temps, relatively high efficiency
#2
mash
vorlauf and drain
add half sparge amount @ 185F, stir, vorlauf, drain
add second half sparge amount @ 185, stir, vorlauf, drain
3 runnings at progressively higher temps, very high efficiency